1. Field of the Invention
The present invention relates to an apparatus and method for transmitting an UpLink (UL) pilot using a scanning interval in a mobile communication system. More particularly, the present invention relates to a scanning apparatus and method for a handover taking into consideration both UL and DownLink (DL) channel states between a Mobile Station (MS) and a Base Station (BS).
2. Description of the Related Art
In a cellular mobile communication system, a user of a subscriber terminal is provided service by a serving Base Station (BS). In such a system, a user may continue a conversation or other use of their subscriber terminal while they are traveling or otherwise in motion. However, a subscriber terminal may encounter a situation in which the communication environment with a neighboring BS is better than that of the serving BS. This may occur for several reasons such as a proximity shift of the subscriber terminal from the serving BS to the neighboring BS, a change of propagation environment, or a sudden increase in the number of subscriber terminals within a specific cell during communication. For example, as illustrated in FIG. 1, during communication with a BS1 103, an MS2 101 can encounter a situation in which the communication environment with a neighboring BS2 105 is better than that of the serving BS1 103. In such a situation, the subscriber terminal, the serving BS, and the neighboring BS must recognize this change of communication environment and establish a new communication path with the optimal BS using a handover from the serving BS to a neighboring BS. Moreover, such recognition and handover must be performed efficiently so that service to the subscriber terminal is not interrupted.
In the conventional art, when there is a request for a handover to a neighboring BS or a neighbor sector according to a change of a user's communication environment, a user subscriber terminal or Mobile Station (MS) measures a channel state with a neighboring BS on the basis of a DownLink (DL) signal from the neighboring BS. Using the channel state information, the MS determines if a handover is appropriate. However, the conventional art has a problem in that handover is decided using only DL channel state information without considering an UpLink (UL) channel state. Accordingly, accuracy decreases and it is difficult to satisfy UL Quality of Service (QoS).